[1]Two German manufacturers, Kann and NightTec, have collaborated to create a pretty cool new product they call “Leuchsteine” or Light Stones.

Put more simply, it’s concrete that glows in the dark.

According to DesignBuild Source[2], phosphorescent crystals embedded in the concrete capture sunlight, store it and then emit light in each night for 10 hours. In the light, the concrete appears white, but when the lights are off it emits blue or green, depending on the variety you choose.

Beyond the cool effect such concrete would produce on interior floors or even pool decks and countertops, there could be more useful applications such as providing direction on staircases or in parking garages toward an exit without the need of sign or anything else that uses electricity.